#include<stdio.h>
int main()
{
    int a=21,i;
    printf("Game begin:\n");
    while(a>0)
    {
        do
        {
            printf("How many sticks do you wish to take(1~%d)?",a>4?4:a);
            scanf("%d",&i);
        } while (i>4||i<1||i>a);
        if(a-i>0)printf("%d sticks left in the pile.\n",a-i);
        if((a-i)<=0)
        {
            printf("You have taken the last sticks.\n");
            printf(" ***You lose!\nGame Over.\n");
            break;
        }
        else
        printf("Computer take %d sticks.\n",5-i);
        a-=5;
        printf("%d sticks left in the pile.\n",a);
        
    }
}
